Bidirectional locking device

ABSTRACT

A bidirectional locking device for an output shaft which has a load impressed thereon is provided by a single spring means placed between the output shaft and a fixed member for normally locking the output shaft and preventing its rotation in either direction; drive means are operatively connected to the single spring means for unlocking the spring means and for driving the output shaft.

lJite uenneville States r Sept. 18, 1973 BIDIRECTHONAL LOCKING DEVICEInventor: Raymond N. Quenneville, Suffield,

Conn.

Assignee: United Aircraft Corporation, East Hartford, Conn.

Filed: Oct. 4, 1971 Appl. No.: 186,380

Related [1.8. Application Data Division of'Ser. No. 58, Jan. 2, 1970,Pat. No.

US. Cl. 192/8 C, 417/319, 310/93 int. Cl 360i 7/112 Field of Search192/7, 8 C; 417/319,

References Cited UNITED STATES PATENTS 4/1935 Miller .L 192/8 cHungerford 192/8 C Primary Examiner-Benjamin W. Wyche Attorney-LaurenceA. Savage [57] ABSTRACT A bidirectional locking device for an outputshaft which has a load impressed thereon is provided by a single springmeans placed between the output shaft and a fixed member for normallylocking the output shaft and preventing its rotation in eitherdirection; drive means are operatively connected to the single springmeans for unlocking the spring means and for driving the output shaft.

5 Claims, 4 Drawing Figures Patented Sept. 18, 1973 4 Sheets-Sheet 1Patented Sept. 18,1973

4 Sheets-Sheet 2 Patented Sept. 18, 1973 3,759,358

' l BIDIRECTIONAL LOCKING DEVICE CROSS-REFERENCE TO RELATED APPLICATIONThis application is a division of my copending application Ser. No. 58,filed Jan. 2, 1970 and now US. Pat. No. 3,631,951.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to a load-holding device and particularly to a.two-directionallocking device which allows an input shaft to drive an output shaft, butwhich prevents the output shaft load from driving the input shaft ineither direction.

2. Description of the Prior Art Friction disk brakes have been utilizedin the past for holding loads. However, such braking systems havecertain disadvantages. Namely, friction disk brakes are affected byambient temperature changes, friction coefficient changes and wear ofthe friction surfaces. To assure that a friction disk brake fulfills thedemand of the particular system upon which it is toact, certainobjectives must be achieved: the coefficient of friction must beaccurately established; this applies to both the absolute value and themaximum variation of static and dynamic values. The values of thecoefficient of friction must remain within the predicted range under theinfluence of all environmental effects. The wear of friction surfaceswith use must be minimized to preclude periodic replacement of thebrakes, and to prevent introduction of contamination which couldadversely affect bearings and gears within the system. Finally, greatpains must be taken to assure efficient cooling of the brake surfacebecause if cooling is not properly achieved, the coefficient of frictionwill in general drop and may remain at the lower level. The heatgenerated in a friction-diskbrake, which is holding a shaft upon whichis impressed a load attempting to rotate the shaft (when the load islowered with the friction brake), is not equal to the energy of thelowered load, but is a function of the range of the coefficient offriction. Therefore, the energy which must be dissipated in the frictiondisk brake can be higher than the actual energy of the lowering load. 7

Two-directional no-back spring clutches are also known in the art.However, the types, known require the use of two springs, one to lockthe load in each direction, thereby being unduly complex and ofexcessive weight.

SUMMARY OF TI-IE INVENTION One object of the present invention is toprovide a bidirectional locking device for an output shaft whichutilizes a single spring means to prevent the output shaft from rotatingin either direction under the action of a load impressed thereon.

It is another object of the present invention toprovide a bidirectionallocking device for an output shaft which is capable of releasing anoverhauling load in either direction with an input force which isindependent of the overhauling load.

It is another object of the present invention to provide a bidirectionallocking device for an output shaft which is capable of absorbing theenergy of an overhauling load by friction in the single spring means.

It is also an object of the present invention to provide a bidirectionallocking device for an output shaft which is capable of absorbing theenergy of an overhauling load in a hydraulic pump, and in the event offailure of the hydraulic element, which is also capable of absorbing theenergy by friction in the single spring means.

It is another object of the present invention to provide a bidirectionallocking device for an output shaft which does not rely on control of thecoefficient of friction range for holding the load and in which the heatenergy absorbed in lowering a load is always equal to the energy of theoverhauling load itself.

In accordance with the present invention a bidirectional locking devicefor an output shaft which is adapted to be driven by input drive meansand which has a load impressed thereon tending to rotate the outputshaft is provided by a single spring means which is engageable with aperipheral surface of the output shaft and a fixed member so asto'normally prevent rotation of the output shaft in either direction.Means are provided for releasing the single spring means from itslocking relationship with the output shaft. The releasing means isactivated by an input drive means so that the output shaft is able tomove only in response to motion of the input drive means.

In further accord with the present invention the bidirectional lockingdevice is capable of releasing an overhauling load with an input forcewhich is independent of the overhauling load. In other words, the forceexerted by the input drive means to release the single spring means fromits locking relationship with the output shaft is independent of theload on the output shaft. Therefore, only a very small force (negligiblewhen compared to the load on the shaft) is needed to release the singlespring means.

In still further accord with the present invention, a hydraulic pump isoperatively connected to the output shaft for absorbing the energy of anoverhauling load. An overhauling load is the load whichis impressed onthe output shaft. When the load-is lowered, it is aiding the input drivemeans to rotate the output shaft. The

energy produced by the lowering load is absorbed by a A hydraulic pumpin order to reduce the heat that would be generated at the spring meansif there were no means for absorbing the energy. The pump operates onlywhen the load is overhauling and notwhen the input drive means israising the load.

The foregoing and other objects, features and advantages of the presentinvention will become more apparent in light of the following detaileddescription of a preferred embodiment thereof as illustrated-in theaccompanying drawings.

, DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of oneembodiment of a bidirectional locking device in accordance with thepresent invention;

FIG. 2 is a perspective view of another embodiment of a bidirectionallocking device in accordance with the present invention; and

FIG. 3 is a perspective view of a third embodiment of a bidirectionallocking device in accordance, with the present invention.

FIG. 4 is a perspective view of a fourth embodiment of a bidirectionallocking device in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there isshown a rotatable output shaft 2 and single spring means 4 operativelyconnected to input drive means 6. Afixed member 8 surrounds the springmeans 4. A load 10 is impressed on the output shaft '2. It should benoted that while the load is shown simply in schematic form as a weightsuspended from a cable wrapped around the output shaft 2, the load couldbe any force which tends to rotate the output shaft, and it could be aload capable of rotating the output shaft 2 in either direction. Aperipheral surface 20 of the output shaft 2 is engageable with thespring means 4.

' As is apparent from the drawing, the output shaft 2 cannot rotateunder the influence of the load 10 because the peripheral surface 20 ofthe output shaft engages end 28 of the spring means 4; the greater theload 10, the more the surface 20 pushes against the end of the springmeans 4, thereby driving the spring means 4 into a force fit with thefixed member 8 and friction between the spring means 4 and the fixedmember 8 locks the load. If the load were reversed, i.e., tending torotate the shaft 2 in the opposite direction, the same locking processwould ensue.

When it is desired to rotate the output shaft 2 to raise or lower theload, the input drive means 6 is rotated in the appropriate direction.For example, when it is desired to lower the load, the input drive meansis rotated counterclockwise (as viewed from the output shaft in FIG. 1).Leg 22 of' the input drive meanswill engage the end 24 of the springmeans 4 and wind the spring means up, thereby releasing the spring meansfrom its engagement with the fixed member 8; the force of the springmeans on the fixed member 8 will thereby be released, and the springmeans is free to rotate with the input drive means 6, and thereby todrive the output shaft 2 through the engagement of the end 24 on theperipheral surface 20 of the output shaft 2.

I It will also be noted that the load cannot be lowered at a rate fasterthan that dictated'bythe input drive means 6 because if the output shaft2 rotates faster than the spring means 4, the peripheral surface 20 ofthe output shaft will engage the end 28 of the spring means 4, therebyexpanding the spring means, and providing friction braking of the outputshaft. The energy of the overhauling load is converted to heat throughfriction.

To raise the load the input drive means rotates in the clockwisedirection (as viewed from the output shaft in FIG. 1). Leg 26 ofthe'input drive means 6' will engage end 28 of the spring means 4 andwind the spring means up, thereby releasing the spring means from itsengagement with the fixed member 8. The input drive means is thusable todrive the output shaft 2 through the spring means 4.

Also, the output shaft 2 may be operatively connected to a hydraulicpump unit, shown generally by the numeral 11. The pump 12, connected tothe output shaft via shaft 14, may pump hydraulic fluid (not shown) fromconduit 16 through the pump 12 and a pressure relief valve l9'or anorifice (not shown) and conduit 18. A heat exchanger 21 may beinterposed between the conduit 18 and the conduit 16 if necessary tocool the hydraulic fluid. The pump 12 may be operated only when the loadis overhauling, i.e., when the input drive means 6 rotates the outputshaft 2 in the direction in which the load impressed on the output shafttends to rotate the shaft by including a bypass valve (not shown) or thepump may pump fluid in either direction.

The pump converts the energy of the overhauling load directly into atemperature rise in the oil being pumped by the hydraulic pump. Byutilizing the pump, the spring means absorbs a minimum of energy andconsequently does not suffer from wear or heat generation. However,should the pump fail, the spring means is capable of absorbing theenergy by friction. While the pump unit 11 is shown only in FIG. 1, itwill be obvious to one skilled in the art that it can be connected tothe output shaft in any other embodiment of my invention for a likepurpose.

Referring now to FIG. 2, an input drive means, shown generally by thenumeral 29, includes motor means 30 which is adapted to drive an outputshaft 32 through a drive gear 34, and a relatively stationary portion46, explained hereinafter. A load 36 on the output shaft 32 is shownschematically as a weight 38 attached to a cable which is wrapped aroundthe output shaft. Single spring means 40 is disposed between aperipheral surface 42 of the output shaft and a fixed member 44. Therelatively stationary portion 46 of the input drive means 29 has legs 48and 50 engageable with ends 52 and 54, respectively, of spring means 40.The relatively stationary portion 46 may be operatively connected to thecasing of the motor means 30 so that the reaction torque of the motormeans 30 rotates the relatively stationary portion 46 to unlock thespring means and permit the motor means 30 to drive the output shaft 32.In this embodiment the spring means does not rotate.

FIG. 3 shows another embodiment of the invention. A single spring means60 is disposed between an output shaft 62 and a fixed member 64. A load66 impressed on. the output shaft 62 is shown schematically as a weightattached to a cable wrapped around the output shaft. The. input drivemeans 68 has legs 70 and 72 engageable with ends 74 and 76,respectively, of the spring means 60. To lower the load, for example,the input drive means 68 rotates counter-clockwise (when viewed from theoutput shaft in FIG. 3). The leg 72 will engage the end 76 of the springmeans 60 and uncoil the spring means, thereby releasing the frictionforce between the spring means 60 and the fixed member 64. The inputdrive means 68 is thenable to drive the output shaft 62 through thespring which rotates therewith. To raise the load, the reverse of theabove would take place.

In FIG. 4 there is shown generally an input drive means 79 includingmotor means 80 having a drive shaft 82 which may be integral with theoutput shaft 84. A relatively stationary portion 86 is operativelyconnected to the motor means 80 and has legs 88 and 90 which areengageable with the ends 92 and 94 of the single spring means 96,respectively. The single spring means is disposed between the outputshaft 84 and a fixed member 98. A load impressed on the output shaft isshown schematically as a load suspended by a cable wrapped around theoutput shaft 84. To raise the load, the drive shaft 82 of the motormeans 80 is rotated clockwise (as viewed from the output shaft in FIG.4). The relatively stationary portion 86 will rotate counter-clockwisebecause it is operatively connected to the housing of the motor means,and the reaction torque of the motor means will cause it to rotate inthe opposite direction of the output shaft 82. The leg 88 will engagethe end 92 of the spring means 96 and release the locking force of thespring means on the output shaft 84 thereby allowing the output shaft torotate in a clockwise direction. To lower the load, the reverse of theabove would take place.

There have thus been described embodiments of my invention. I wish it tobe understood, however, that I do not desire to be limited to the exactdetails of construction shown and described, for obvious modificationswill occur to a person skilled in the art.

What l claim as new and desire to secure by Letters Patent of the UnitedStates is:

LA bidirectional locking device for an output shaft having a loadimpressed thereon tending to rotate the output shaft, comprising:

input drive means including a motor means having a movable po'rtion anda relatively stationary housing having slight oscillatory movementsupporting said movable portion;

a fixed member disposed adjacent said output shaft and spaced therefrom;

a single spring means engageable with a peripheral surface of saidoutput shaft and with said fixed member, saidspring means normallylocking said output shaft and thereby preventing its rotation in eitherdirection; and

releasing means movable in response to a reaction force induced in saidrelatively stationary housing of said motor means in response tomovement of said movable portion of. said motor means for releasing saidspring means from its locking relationship with said output'shaft andsaid fixed member whereby said output shaft rotates only in response tomovement of said input drive means;

and a pump operatively connected to said output shaft and adapted to bedriven thereby in response to rotation of said output shaftby said inputdrive means in the direction which the impressed load tends to rotateit, whereby said pump absorbs the energy of the overhauling load.

2. A bidirectional locking device for an output shaft which is adaptedto be driven by an input drive means, and which has a load impressedthereon tending to rotate the output shaft, comprising:

a fixed member coaxially disposed in a bore of said output shaft andspaced therefrom;

single spring means disposed in said. space adjacent said fixed memberand said'output'shaft so as to .bear against the outer periphery of saidfixed memher and so as to be engageable with an inner peripheralsurface'of said output shaft for normally locking said output shaft andthereby preventing its rotation in either direction; and

input drive means including a motor having a relatively stationaryhousing but being capable of slight oscillatory movement and a rotatingdrive shaft, said housing being operatively connected to said singlespring means for releasing said single spring means from bearing againstsaid fixed member, whereby said output shaft rotates only in response tomotion of said input drive means.

3. A bidirectional locking device for an output shaft as defined inclaim 2, additionally comprising:

a pump operatively connected to said output shaft and adapted to bedriven thereby in response to rotation of said output shaft by saidinput drive means in the direction which the impressed load tends torotate it, whereby said pump absorbs the energy of i the overhaulingload.

4. A bidirectional locking device for an output shaft which is adaptedto be driven by an input drive means, and which has a-load impressedthereon tending to rotate the output shaft, comprising:

a fixed hollow cylindrical member surrounding said output shaft andspaced therefrom;

single spring means disposed in said space adjacent said fixed, memberand said output shaft so as to bear against said fixed member and so asto be en'- gageable with a peripheral surface of said output shaft fornormally locking said output shaft and thereby preventing its rotationin either direction; and

input drive means including a motor having a housing and a drive shaft,said housing being operatively connected to said single spring means forreleasing said single spring means from its engagement with said outputshaft by the reaction force when the drive shaft is rotated in eitherdirection, whereby said output shaft rotates only in response to motionof said input drive means.

5. A bidirectional locking device for an output shaft as defined inclaim 4, additionally comprising:

a pump operatively connected to said output shaft and adapted tobedriven thereby in response to rotation of said output shaft by saidinput drive means in the direction which the impressed load tends torotate it, whereby said pump absorbs the energy of the overhauling load.

1. A bidirectional locking device for an output shaft having a loadimpressed thereon tending to rotate the output shaft, comprising: inputdrive means including a motor means having a movable portion and arelatively stationary housing having slight oscillatory movementsupporting said movable portion; a fixed member disposed adjacent saidoutput shaft and spaced therefrom; a single spring means engageable witha peripheral surface of said output shaft and with said fixed member,said spring means normally locking said output shaft and therebypreventing its rotation in either direction; and releasing means movablein response to a reaction force induced in said relatively stationaryhousing of said motor means in response to movement of said movableportion of said motor means for releasing said spring means from itslocking relationship with said output shaft and said fixed memberwhereby said output shaft rotates only in response to movement of saidinput drive means; and a pump operatively connected to said output shaftand adapted to be driven thereby in response to rotation of said outputshaft by said input drive means in the direction which the impressedload tends to rotate it, whereby said pump absorbs the energy of theoverhauling load.
 2. A bidirectional locking device for an output shaftwhich is adapted to be driven by an input drive means, and which has aload impressed thereon tending to rotate the output shaft, comprising: afixed member coaxially disposed in a bore of said output shaft andspaced therefrom; single spring means disposed in said space adjacentsaid fixed member and said output shaft so as to bear against the outerperiphery of said fixed member and so as to be engageable with an innerperipheral surface of said output shaft for normally locking said outputshaft and thereby preventing its rotation in either direction; and inputdrive means including a motor having a relatively stationary housing butbeing capable of slight oscillatory movement and a rotating drive shaft,said housing being operatively connected to said single spring means forreleasing said single spring means from bearing against said fixedmember, whereby said output shaft rotates only in response to motion ofsaid input drive means.
 3. A bidirectional locking device for an outputshaft as defined in claim 2, additionally comprising: a pump operativelyconnected to said output shaft and adapted to be driven thereby inresponse to rotation of said output shaft by said input drive means inthe direction which the impressed load tends to rotate it, whereby saidpump absorbs the energy of the overhauling load.
 4. A bidirectionallocking device for an output shaft which is adapted to be driven by aninput drive means, and which has a load impressed thereon tending torotate the output shaft, comprising: a fixed hollow cylindrical membersurrounding said output shaft and spaced therefrom; single spring meansdisposed in said space adjacent said fixed member and said output shaftso as to bear against said fixed member and so as to be engageable witha peripheral surface of said output shaft for normally locking saidoutput shaft and thereby preventing its rotation in either direction;and input drive means including a motor having a housing and a driveshaft, said housing being operatively connected to said single springmeans for releasing said single spring means from its engagement withsaid output shaft by the reaction force when the drive shaft is rotatedin either direction, whereby said output shaft rotates only in responseto motion of said input drive means.
 5. A bidirectional locking devicefor an output shaft as defined in claim 4, additionally comprising: apump operatively connected to said output shaft and adapted to be driventhereby in response to rotation of said output shaft by said input drivemeans in the direction which the impressed load tends to rotate it,whereby said pump absorbs the energy of the overhauling load.